Drafting machine



Oct. 3l, 1939.. c. ||A LITTLE l v DRAFTING MACHINE Filed Aug. 5', 1933 5Sheets-Sheet l Tv, m awww www ATTORNEYS Oct. 3l, 1939. c, H LITTLEDRFTING MAC'IINE Filed Aug. 5, 1933 5 Sheets-Sheet 2 @fw/f f E w i@ hwkum M.

A r rok/ve Ya Oct. 31, 1939. c;v LlTTLE 2,178,045Y

DRAFTING MACHINE Filed Aug. 5, 1933 f 5 Sheets-Sheet 3 /Nve/vroe CHA@L55 M L /rr/.c

s45/uf ATTORNEYS Oct. 31, 1939. c. HA LITTLE DRAFTING MACHINE Filed Aug.5, 1933 5 vShelves-Sheet 4 s elwdw ma N vs m Ww r .A

Oct. 31., 1939. c H.V LITTLE DRFTING lMC'IINE Filed Aug. 5, 1933 5Sheets-Sheet 5 /Nvawraef Clanes/l I1-125 f@ www 55 ing a wheel and bandtype arm in which the band Patented Oct. 1939, i

. UNITED -'STATES PATENT" UFFICE" y signoi'- of one-tenth.

to Charles Hubbard Little, Cleveland Heights, hio y Application August5, 1933,' Serial No. 883,773

18.(2lllml.

The present invention relates 'to tdrafting machines of the parallelmotion type, wherein an arm comprising a plurality of connected sectionsf or parallelograms is employed to maintainparallelism of rulers andprotractors as they are moved about a drawing board, and particularly tothose drafting machines wherein the sections or parallelograms are ofthe wheel and band type.

A very high degree of accuracy is required in machines of thischaracter, and due to the particular construction thereof, slight errorsor changes inthe various parts, especially the parallelograms, resultsin multiplied errors at the rulers.

' made to give very accuratev parallelism to the rulers but their usehas been very limited because of the elasticity ofthe bands whichresults in instability or springiness at the endsof the rulers.

The present. invention overcomes this serious= defect withoutinterferingwith the free andk easy movement ofthe arm, which isessential 'for both accuracy and convenience of operation.

Arms of the wheel and band type usually coinprise two sections orparallelograms, each of which comprises a pair of equal diameter wheelsrotatably connected to each other by either a :singleor double strut andcarrying a taut band.

An object of the present invention is the provision of a band for awheel and band type parallel motion mechanism that will have a highresistance to tension, compared with its resistance to turning about thewheels, and also'not require excessive tension to keep it taut. A numberof means for obtaining this result will be herein described but thepreferred construction consists of a single band of flexible materialwrapped several times about the wheels. with the ends andcertainintermediate parts thereof kclamped or fastened 0 to the wheels. Theband may be provided with transverse curvature, which constructionreduces the amount of tension required tol-reep the same taut, and alsotends to keep the several layers in alignmentwith eachother.. Multiplebands are 45 also shown, which'have a larger cross-section between thewheels thanthat of the portion which -turns aboutzthe wheels, providedwith adjusting means for' 'properly distributing the stresses among theseveral bands. This latter construc- 50 tion is very advantageous inarms having longer sections 'or parallelograms than are ordinarily used.

Another object of the present invention is the provision of a noveldrafting machine, compris- Arms of the wheel and bandtype can be has ahigh resistance to tension, compared to its resistance to turning aboutthe wheels.

Another o bject of the present invention is the provision of a noveldrafting machine of the parallel motion type in which the protractor andhandle lie much closer to the drawing board than 'the protractor andhandle vof machines of the prior art.

Another object of the present invention is the provision of a noveldrafting machine of the parallel motion type comprising a wheel and bandtype-of arm in which the center of the protractor is external of theband. Y

Further objects and advantages of the invention will be apparent tothose skilled in the art from the following description of the preferredembodiments thereof described with reference tothe accompanyingdrawings, in which Fig. 1 is aplan of a drafting machine embodying thepresent invention,attached to a drawing Fig. 2 is a side elevation ofthedrafting machine and drawing board shown in Fig. 1;

Fig. 3 is a section on the line 3.3 of Figs, 1 and 4, with portions inelevation;

Fig. 4 is a section on theline 4-4 of Fig.;3, with portions inelevation;

Fig. 5 is a plan of the band shown in Figs. 1 to 7 inclusive;

Fig. 6 is an enlargement of a portion of Fig. 1;

Fig. 7 is a section on the line 1--1 of Figs. 1, 2 and 6;

Fig. 8 is a section similar to Fig. 'I illustrating a modiedconstruction of band;

Fig. 9 is asection similar to Figs. 'I and 8 illustrating a furthermodified construction of band;

Fig. 10 is a plan of a modified construction of .v

drafting machineembodyingthe present invention: l

11 is an enlargement of a portion of Fig. l10::y

mg. 12 is section onine une larl2 of Fig. v1'1 is an enlargement of oneof the adjustable inserts shown in Fig. 13.

Similar reference characters designate corre- 1 The anchor D is orwellknown construction, and

per se forms no part of the present invention and will not be describedin detail, suffice it to say that the same is slidably supported on andadjustable along a bar I attached to the underside of the board B bybrackets II.

The anchor parallelogram comprises two wheels I3 and I4 of equaldiameter. The upper wheel I3 is fixed to a member I5 pivotally connectedto the anchor D in a manner well known in the art, and the lower wheelI4 is connected to a tubular shaft I5, by means of anti-frictionbearings I 1. The wheels I3 and I4 are spaced apart by means of anadjustable strut I9 provided with forked end members and 2|. The upperend member 2|) projects to either side of the wheel I3 and is rotatablyconnected thereto by means of anti-friction bearings in such a mannerthat 45 `antifriction bearings 32, and the right-hand it is free tooscillate about the center thereof as an axis. The lower forked endmember 2| is connected to the tubular shaft I6 upon which the wheel I4is rotatably supported.

The wheels I3 and I4 are joined by a flexible band in such a manner thatthe wheel I4 does not rotate with reference to the drawing board B andthe wheel I3, as the strut I9 is oscillated about its pivotedconnection. The band 25 runs between flanges on the periphery of theWheels I3 and I4 which assist in retaining the band in position on thewheels, and is connected to each wheel in a manner hereinafter referredto.

The protractor parallelogram comprises two wheels and 3| of equaldiameter and similar in construction to the wheels I3 and I4 of theanchor parallelogram. The left-hand wheel 3|! is rotatably connected toa tubular shaft 29 by wheel 3| is pivotally supported by anti-frictionbearings, in a forked end member 33 of an adinstable strut 34 similar inconstruction to the strut I9 previously referred to. The other extremityof the strut 34 is provided with a forked end member 35 which extends oneither side of the wheel 30 and' is connected to the tubular shaft 29 insuch a manner that the strut 34 is free to oscillate about the axis ofthe wheel 30.

The wheels 30 and 3| are joined by a exible band 38, similar to the band25, in such a manner that the wheel 3| does not rotate with rei'- erenceto the drawing board B and the wheel 30, as the strut 34 is oscillatedabout its plvoted-connection with the tubular shaft 29. The flexiblebands 25 and 38 each comprise a single strip of thin flexible material,preferably steel, Wrapped about the wheels I3 and I4, and 30 and 3|,respectively, a plurality of times. As illustrated, see Figs. 3 and 4,the strips are wrapped about their respective wheels four times. Bothends of the strip which forms the band 38 are attached to the wheel 30by means of a screw 40 which extends through elongated slots 4I formedin the strip, and the wheel 3| is attached to the band 38 in a similarmanner by a screw, not shown, which projects through the elongated slots42. The strip which forms the band 25 is attached to the wheels I3 andI4 in a similar manner,

The struts I9 and 34 are adjustable for the purpose of assembling thebands on the wheels, and for taking up slack and producing tension inthe band. In the embodiment of the invention illustrated, theconstruction of both struts is the same and the adjustment isaccomplished by turning a tubular member 43, see Fig. 4, threaded intothe interior of the tubular strut member. A head 44 on the member 43abuts against the adjacent forked end member which is'prevenied fromturning with reference to the strut by a pin 45. The pin 45 is securedin the tubular strut member and projects through a slot 46 in a shortshaft 41 fixed to the forked end member. The tubular member 43 isprovided with a knurled hand grasp 48 for easy operation thereof, soconstructed that it entirely conceals the thread in all workingpositions. The bands are adjusted to obtain theproper distribution oftension between the different layers by loosening the screws whichattach the same to the wheels, and alternately applying and releasingthe tension thereof and oscillating the sections or parallelograms. Theelongated slots in the strips through which the screws pass permit thedifferent layers of the band to adjust themselves after which thescrewsare tightened and the band held securely to the wheels-independent ofthe friction between the band and vthe wheels. Clips 49 are preferablyemployed to-'keep the different layers of the band-in alignment, butthese clips may be omitted if desired. The clips 49 permit longitudinalmovement of the bands relative to each other, and may beheld fromlongitudinal movement along the bands in any convenient manner.

It has been found that one-piece flexible bands wrapped about the wheelsa number of times produce a very practical, cheap, and simple band whichgives a high degree of stability at the outer end of -the sc aleswithout adversely affecting the ease of motion of the arm. MultipleVbands greatly increase the stability or lack oi springiness at the outerend ofthe rulers by permitting a sufficiently large section to beemployed to prevent undue stretch between the wheels without materiallyincreasing the turning resistance when the band wraps and unwraps aboutthe wheels, because the moment of resistance varies as the square of thelayer thickness. This construction also reduces the amount of tensionrequired to keep the bands taut and in turn the stresses in the partsbetween the wheels and the load on the bearings,retc. Attaching thebands to the wheels by means of the screws 40 also reduces thesestresses by doing away with the necessity of sufficient friction toprevent the wheels from turning in the bands. The tension in the bandsand the stress in the struts often exceeds 200 pounds, and any reductionin the stresses to which the various parts are subjected results ineasier turning.

The wheels I4 and 30 are connected together by screws 50 in such amanner that they move as a unit. The position of the screw 50 is limitedby the extreme positions of the struts I9 and 34, shown in dotted linesin Fig. 4, as they osclllate a maximum '.of approximately 180. A spacercollar 5|` is employed to keep the wheels in proper spaced relationship.

A member secured to the underside of the wheel 3| carries the protractorassembly A detachably secured thereto by screws 56. The protractorassembly is of well known construction and per se does not form a partof the present in- CII vention and will not be described in detail,suice 38 which construction permits the handle 58 and' .the hand to liemuch closer to the drawing and avoids any'interfe'rence of the handofthe operator with the band or wheel. This construction is alsoladvantageous when working at the left hand part of the drawing,especially in angular positions, as it places the rulers further fromthe bands.

Figs. 8 and 9 illustrate two modified constructions of bands 63 and 64which'may be employed in place of the bands shown in Figs. 1 to '1inclusive. The bands 63 and 64 are similar to the bands 25 and as shownin'Figs. 1 to 7 inclusive,

except for the fact that the bands 63`and 64 are transversely curved. InFig. 9 one of the layers of the band 64 is shown curved in a reversedirection. Transversely curving the bands as illustratedhn Figs. 8 and 9assists in keeping vthe various layers in alignment and reduces theamount of tension necessary to keep the bands taut. In some light, smallmachines, particularly when the transverse curved bands are employed,pin bearings may beused in place of the ball bearings illustrated, thussimplifying the construction and lowering the cost of the machine..

The construction shown in Figs. 1 to 10 inclusive is claimed in mycopending application Ser.y No. 50,215, filed November 16, 1935,kentitled Drafting machine.

Figs. 10 to 12 inclusive illustrate a modified construction of thedrafting machine shown in Figs. l'to 7 inclusive. The drafting machineillustrated in these iigures is similar in construction to that shown inFigs. 1 to 7 inclusive and the duplicate parts are indicated by the samereference characters. In place of the multiple bands and 38 employed inthe drafting machine rst described, multiple bands 61 and 68 of modifiedconstruction are employed. bands 61 and 68 each comprise a plurality ofthin exible strips, one or more of which are provided with insertshaving a larger area of cross section than that of the strip proper,and, therefore, less stretch per unit length than the strips themselves.In the embodiment illustrated three strips 10, 1| and 12 are shownalthough any desired number may be employed.

The outer and inner strips 10 and 12 are connected to parts or inserts13 and 14 as illustrated. The inserts 13 are made of two parts threadedin opposite directions and connected by a turnbuckle 15. One of theseinserts 13 is placed in ,each of the inner and outer strips of the bandso that they may be adjusted for length and the stress in the band`equally distributed between the various strips or layers. While noinserts are illustrated in the center strip 1| it will be understoodthat inserts may ber employed in this strip if de'- sired. The bands arepreferably attached to the wheels in a manner similar to that describedwith reference to the bands 25 and 38.

The wheel 16 located atfthe free or protractor end of the arm is similarin construction to wheel 3| previously referred to, except that it isprovided withv a rotatable center 11 adapted to be clamped in anyadjusted position by screw clamps The protractor assembly A is connectedto a member 1 9 attached to the rotatable center 11 of the wheel 1'6,and may be adjusted about the center lof the wheel 16 as an axis. Y

lThe

beingequal. With the larger wheels it is also The strut 80 in theprotractor section or parallelogram is the same in construction as thestrut 34 previously. referred to. except that the forked end member 33of the strut 34 is replaced by an end rmember 8| provided with twospaced rollers 5` 82 which engage the periphery of the wheel 16. Amember 83 fixed to the end member 8| pro# jects underneath the wheel 16between the same and a depressed portion 84 yof the member 19. Themember 83`does not normally bear against either the wheel 16 or theportion 84 of the member 19 but prevents the wheel from snapping out ofposition at right angles to the drawing board.

A modified construction of drafting machine having a protractorespecially adapted for civil engineering and navigation work, and havingits center coincident with the center of the Wheel at the free orprotractor end of the arm, is illustrated in Figs. 13 to 17 inclusive.The draftingdm'fl chine illustrated in these iigures is similar inconstruction to the machines previously referred to. and duplicate partsarel indicated-by the same reference characters. j.. The anchorparallelogram comprises a wheel 90;,129tatably connected to a member 9|pivotally connected to the anchor D, and is adapted to be held in anyadjusted position by a thumb screw 92, threaded into an aperture in themember 9| and extending through an arcuate slot 93 in the wheel. f

An adjustable strut 95, similar in construction to the strut 80previously referred to, is pivotally connected to the center ofthe wheel90. Rollers 96 carried by the strut 95, engage the periphery of acylindrical memberor wheel 91 the diameter of which is equal to thediameter of the wheel 90. The cylindrical member or wheel 91 is twicethe thickness of the wheel 90 and is common to both the anchor,and'protractor sections or parallelograms. The wheel`91 is joined tothe wheel 90 and held in engagement with the rollers 96 by means of amultiple band 98 similar in construction to the bands 61 and 68 exceptthat the inserts 13 are replaced by short inserts 99 and the inserts 14are omitted altogether, giving the machine a larger range of movement.The insertsv 99 are employed for the purpose of adjusting the length ofthe inner and outer layers of the band A to the length of the centerlayer. so that each layer will take its proper proportion of the load.

They protractor section or parallelogram comprises a wheel 00, and anadjustable strut |0| both ends of which are provided with rollers |02 inengagement with the-periphery of the cylindrical member or wheel 94 andthe periphery of the wheel |00. The wheel |00 is joined to thecylindrical member or wheel 94 by a multiple band |03 similar inconstruction. to the band 98. The bands 98 and |03 :are preferably notconnected to the respective wheels with which they engage and themovement of the struts is notllmited thereby. The elbow of thearm maythrow to the opposite side of the center line between the` wheels 90andk |00, thus making it possible to get parts of the arm out of the wayof the rulers when workng in certain positions. The loss of stability atthe outer end of the rulers due to the omission of the long inserts oflarger area of cross-section between the wheels, is compensated for bythe fact that it is desirable to use larger wheels' on account of thelarge size protractor used for civil engineering work, inasmuch as thestability of the outer' end of the rulers is proportional to the squareof the diameter of the wheels, other things posible to use thickermaterial for'the bands since the bend is not as sharp.

Members Ill and |00, similar in construction, are attached to the ly,kat the ends thereof 'adjacent the cylindrical memberv or wheel 01. Themember |05 projects over the wp surface of the wheel 91 and extendsunderneath a plate |01 secured to the top of the wh'eel. Ihe member |00projects over the under surface of the whel 01 and extends above a plate|00 securedto the underside ofthe wheel 01. The members |00 and |00 donot normally engage against either the plates |01 and |00, respectively,or the wheel 01, but prevent the wheel fromv snapping out of position atright angles to the drawing board.

A vprotractor' ring II! is rotatably set in the wheel |00 and adapted tobe clamped to the wheel in any position by clamping screws I I0. Thesetting of the protractor ring is read froma'deadline mark on a memberIll nxed to the wheel |00. The inner diameter of the protractor ring .II2 is made with a V-shape and tits into a corresponding groove in theperiphery of a ring composed of four segments III, III, ||1 and IIIadjustably connected to a central plate |20 by eccentric rivets III. andan eccentric clamp |22 by which it may be radially locked in anyposition. A handle |20 is secured to thecentral plate |20 by screws |20.A ruler plate |20 is connected to the central plateil by screws |20 andheld in proper spaced relation by tubular members |00. A member attachedto the underside of the strut |0| projects beneath the wheel |00 andabove the ruler plate |20. The member |00 normally does not engageeither the wheel I 00 or the ruler plate |20, but prevents the wheel |00from snapping out of position at right angles to the drawing board.

A spring pressed pawl |05, operated by a thumb piece |00, engages slotsin a ring |01 attached to the underside of the protractor ring III, togive zero, 30, 45, `60 and 90 degree angles as desired. The rulers areindicated by the reference characters |30 and |00. The protractorillustrated is very light and substantial in construction, and does notinterfere in any way with any part of the wheel or arm.

The protractor and handle are set very low with reference to thedrawing. The construction permits the protractor. ring to be set at anydesired angle, which is always shown. This is a very desirable featurein a number of instances, for example, the correction of the compassreading at any particular point may be made by turning the ring tocompensate for the correction, and then clamping it in position. Thereadings are then direct and the amount of the correction is alwaysclearly shown.

The preferred embodiments of the present invention have been illustratedand described, but I do not wish to be limited to the particularconstruction illustrated, which may be varied within the scope of thisinvention. It is my intention to cover in as broad a way as possible theadvantage of the easy moving, stretch resisting bands,

giving a high degree of accuracy and stability,

and the advantages of low lying protractors, free from interference withthe arms. VI particularly point out and claim as my invention thefollowing:

l. In a parallel motion mechanism for a drafting machine-or the like, aplurality of wheels, a plurality of bands extending around said wheels,and means for adjusting the length of some of struts 05 and lill,respectivev said bands whereby the stresses in the different bands maybe equalized.

2. In a parallel motion mechanism for a drafting machine or the like,the combination of a plurality of wheels, a band extending around saidwheels, a strut connected to said wheels for holding the same in spacedrelationship, and a plurality'of rollers interposed between said strutand `the periphery of one of said wheels.

3. In a drafting machine the combination of a parallel motion arm, aruler assembly rotatably connected to one end of said parallel motionarm, a friction clamp slidably supported for movement radially withreference to the axis about which said ruler assembly isrotatablysupported, and means for moving said clamp'radi'ally to clamp said rulerassembly within said arm.

4. In a drafting machine the combination of a parallel motion arm, aprotractor ring connected to one end of said arm, a ruler assemblyrotatably supported by said arm concentric with said protractor ring, afriction clamp slidably supported for movement radially of the axisaboutv which said ruler assembly is rotatably supported, and means formoving said clamp to clamp said ruler assembly to said arm in anyadjusted position.

5. In a drafting machine the combination of a parallel motion arm, aprotractor ring carried by one end of said arm, a ruler assemblyrotatably supported by said arm concentric with said protractor ring,said ruler assembly comprising a segmental plate, and means for movingone of the segments of said plate radially to clamp said ruler assemblyin any adjusted position.A

6. In a drafting machine the combination of a pair of wheels, a flexibleband extending around said wheels, a strut operatively connected to saidwheels for holding the same in spaced relation, said strut comprisingtelescoped members having threaded engagement with each other forproducing relative longitudinal movement between the same, one of saidmembers having a guard extending over the break between said members for`covering the threads which would otherwise be exposed.

'1. In a device of the character described the combination of a parallelmotion mechanism or arm of the wheel and band type, a member rotatablysupported coaxial with the wheel at one end of the parallel motionmechanism or arm, a second member rotatably supported coaxially with thefirst mentioned member, said first and second member being located atthe upper side of the wheel and a ruler arm at the lower side of thewheel fixed to said second member through the center of the wheel.

8. In a drafting machine, the combination of a parallel motion mechanismof the wheel and band type, a protractor ring rotatably supported by thewheel at the free end of said parallel motion mechanism coaxialtherewith, a second member rotatably supported by said protractor ringcoaxial therewith, said protractor ring and second member being locatedat the upper side of said wheel, and a ruler arm at the lower side ofsaid wheel xed to said second member.

9. In a protractor the combination of a supporting member, an annularmember rotatably supported by said supporting member, a second memberrotatably supported coaxially with said annular member, a handleconnected to said second member, a spring actuated means for holdingsaid annular member and said second member against relative rotation,and a member adjacent said handle for releasing said means.

10. In a protractor the combination of a supporting member, an annularmember rotatably supported by said supporting member, a second memberrotatably supported coaxially with said annular member, a detent carriedby one of said last two mentioned members adapted to engage the otherfor preventing relative rotation between the same.

11. In a protractor the combination of a supporting member, an annularmember rotatably supported by said supporting member, a second memberrotatably supported coaxially with said annular member, a handleconnected with said second member, a spring actuated detent for holdingthe last two mentioned members against relative rotation, and a memberadjacent said handle for releasing said detent.

12. In a protractor the combination of a supporting member, an annularmember rotatably supported by said supporting member, a second memberrotatably supported coaxially with said annular member, a handleconnected with said second member, one of the last two mentioned membershaving a plurality of apertures therein, a detent carried by the otherof said members adapted to engage in said apertures, and means adjacentsaid handle for releasing said detent.

13. In a'protractor the combination of a supporting member, an annularmember rotatably supported by said supporting member, means for clampingsaid annular member against rotation within said supporting member, asecond member rotatably supported coaxially with said annular member, ahandle connected with said second member, spring actuated means forclamping said annular member and said second member against relativerotation, and means adjacent assembly rotatably supported coaxiallywithsaid,

annular member, a handle connected tothe ruler assembly, a springactuated means for holding said annular member and said ruler assemblyagainst relative rotation, and a member adjacent said'handle forreleasing said means.

15. In a protractor the combination of a supporting member, an annularmember rotatably supported by said supporting member, a ruler assemblyrotatably supported coaxially with said annular member, a handleconnected With said ruler assembly, a detent for holding said annularmember and said ruler assembly against relative rotation, and a memberadjacent said handle for releasing said detent. l

16. In a drafting machine the combination of a parallel motion arm ofthe wheel and band type,.a protractor ring member rotatably supported bythe wheel adjacent to one end of said parallel motion arm, a memberrotatably supported coaxially with said protractor ring member, one ofsaid members having a plurality of notches therein, a detent carried bythe other of said members adapted to engage in said apertures forpreventing relative rotation between said members.

1'7. In aA drafting machine the combination of a parallel motion armcomprising a plurality of wheels, an annular protractor member rotatablysupported by the Wheel adjacent to the free end of said parallel motionarm, a ruler assembly rotatably supported coaxially with said annularprotractor member, a handle connected to said ruler assembly, saidprotractor member having a plurality of apertures therein, a detentcarried by said ruler assembly adapted to engage in said apertures, andmeans adjacent said handle for releasing said detent.

18. In a drafting machine the combination of a parallel motion arm ofthe wheel Aand band type, an annular protractor member rotatablysupported by one of the Wheels of said parallel motion arm, means forclamping said annular protractor member against rotation relative to thewheel, a ruler assembly rotatably supported coaxally with said annularmember, a handle connected with the ruler assembly, spring pressed meanscarried by said ruler assembly for clamping said protractor member andsaid ruler assembly againstrelative rotation, and means adjacent saidhandle for releasing the last mentioned means.

CHARLES H. LITTLE.

